Abstract: Post-station project is the most complex and the most extensive work in the process of urban rail transit project construction, and its construction quality directly affects the safety of train operation. Taking Chengdu Metro Line 6 Phase III project as a case study, the optimization of all items in the post-station engineering design with BIM (Building Information Modeling) technology is explored, and specific analysis and research in the aspects of system construction, collaborative design of construction drawings, and output of design results are conducted. Research shows that using BIM technology for design optimization can achieve efficient collaboration between design and construction, greatly improving design efficiency, and the quality of drawings.